The present invention relates to insert, holder and cutting tool using the same.
Conventionally, those manufactured by inserting, into a holder, a substantially rod-shaped insert (hereinafter simply referred to as an insert) that has a cutting edge on both ends thereof, and is clamped by tightening with a bolt, are known as a cutting tool used for grooving an inner diameter or threading.
Patent Document 1, for example, discloses a cutting tool manufactured by inserting, into a hole of a holder, one end of a substantially rod-shaped insert having a cutting edge on both ends thereof. Also, disclosed is that the position in the axial direction of the insert is determined by abutting contacting with a flank surface on one end of the insert against an adjustment member within the holder.
However, although the position in the axial direction is determined with relatively good accuracy, index accuracy regarding the center height of the insert is poor. That is, for determining the position of the center height, a plane (a plane portion on the upper surface side) perpendicular to the center height direction is provided on the outer peripheral surface of the upper side of the insert to press and, for example, clamp the plane portion on the upper surface side by screwing. Therefore, when pressed by screwing, sometimes the insert ends up rotating slightly; hence, experienced training is required to constantly maintain the center height when repeatedly securing the insert. As a result, variations in the accuracy of repetitive mounting become significant. Furthermore, because the plane portion on the upper surface side is provided, the cross-section area of the insert becomes small, resulting in a problem of deterioration in its rigidity.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-71204